The invention concerns a procedure for transferring a measured angle of unbalance position to a correction plane of a rotor to be investigated, whereby no rotating part of the balancing machine rotates synchronously with the rotor to be investigated (balancing machine without drive shaft) and a mechanism for implementing this procedure.
DE-OS No. 2548729 (U.S. Pat. No. 4,064,761) contains information on a procedure for obtaining and indicating the angle position of the unbalance for balancing machines with an angle indicator, particularly for those with shaftless drive of the body to be balanced, which procedure is characterized thereby that the angle of unbalance can be converted and/or indicated in units of length or in non-dimensional units, each one of which relates to a circumference or a characteristic subdivision of the body to be balanced and which comprise a range of 360.degree.. A mechanism for this purpose is also known, characterized by means for converting the measured angle value by at least one calculation magnitude and/or an indicator device for units of length and/or dimensional units. In the area of balancing, this makes it possible to transfer measured angles of unbalance to a rotor to be balanced, namely thereby that the unbalance is converted into a measure of length, the end of which marks the position of the angle of unbalance when it is placed on the circumference of the body, beginning at a zero point set on the body to be investigated, said angle position being the point where a corresponding correction of the unbalance can take place. It is also possible, as clarified in this disclosure document, to apply a counter tape to a rotating body and to utilize this counter tape for determining the position of the angle of unbalance by means of the indicated conversion value, if said tape is related to a specific zero point on the rotating body.
In respect to bodies which have markings at their circumference already from the production process, or which are provided with a counter tape, it will thereby be possible to transfer the indicated angle of unbalance to the body in question. The cited disclosure document also provides information on how to determine the angle of unbalance by means of a carrying roller instead of with a counter tape to be applied to the body to be investigated, since this roller has a specific relation to the bearing neck of the body to be balanced. However, in this case it will be necessary to provide the carrying roller with an angle scale.
Particularly in regard to rotating bodies with varying diameter of the rotating body proper or the bearing neck of the body, considerable time is required in order to prepare the balancing body proper, e.g. by attaching a counter tape which must be brought into agreement with a zero point to be set on the body to be balanced, or by providing an angle scale on a carrying roller for the rotor to be balanced, which scale generally is not easily accessible and, in addition, cannot always be read without errors. In this case it is also necessay to constantly readjust the ratio between the radius of the carrying roller and the radius of the bearing neck, which necessitates a new indicator scale, on which the angle of unbalance must first be read and then subsequently transferred to the rotating body. Precision deficiencies in the transfer of the angle of unbalance to the body to be investigated will be impossible to avoid due to the several manual procedures of reading and of measuring.
An approach is known for detecting the angle of unbalance of a rotor (Japanese Publication No. 106 598/80, European Publication 0045 505), in which the procedure for slowing down the rotating body is initiated and regulated in accordance with a measurement of the unbalance, so that the rotating body comes to a standstill at an angular position which makes possible a determination of this angle. For this purpose an impulse transmitter is coupled with the rotor at a fixed speed or with respect to a friction drive. From this measuring signal--which is filtered if necessary--impulses, like those of known stroboscope machines are derived, which impulses determine the instant of the onset of the retardation. It is assumed that the rotor traveled a certain total angle from this instant to a standstill, and the total angle is controlled with respect to the coupled impulse transmitter.
Difficulties do arise however with this arrangement, because the slippage is not constant over the long term but depends, for example, upon the moment of gyration of the rotor, the temperature, the moment of braking, and fluctuating friction. For this reason this arrangement is especially plagued by deficiencies in the case of a series of unbalances. Furthermore, it is not possible to find the angle of unbalance again without a new measurement-run if the synchronization has been lost at lower rotational speeds. A synchronization is very often required without a renewed measurement run, however, especially if the rotating body should be taken from its bearings for the purpose of correcting the unbalance.
This arrangement leads to even further difficulties, since there normally is interference in the measurement signal which makes insertion of a filter necessary. This filter causes errors if the frequency of unbalance and the filter frequency, which must be closely in tune, are not exactly synchronized.